This invention relates to improvements in precision voltmeters of the type having a bipolar analog input and a digital output indicating the voltage and sign of the differential input. Thus, the voltmeter provides a digital output indicating the difference between the voltages at the two terminals of the bipolar input, and the sign of such difference. Such a precision voltmeter may utilize a series of stages, comprising a differential input amplifier affording a bipolar input, an absolute value amplifier, a voltage-to-frequency converter, a gate system operable by a polarity detector, and an up-down counter which counts up for one polarity and down for the opposite polarity. The voltage-to-frequency converter converts a variable voltage signal into a variable frequency signal. The frequency of the output signal is directly proportional to the voltage of the input signal. The gate system switches the variable frequency signal to the up counter input for one polarity and to the down counter input for the opposite polarity.